A 'Two-For-One' Biocide For Latex Coatings Provides Effective In-Can and Dry Film Preservation
In the early 1970s, the most popular biocides for paints were based on phenyl mercury acetate because they had the appealing ability to serve in the dual capacity of in-can preservative and dry film mildewcide.6-8 However, the toxicity and environmental concerns of mercury-based biocides resulted in the paint industry discontinuing their use in the United States in the 1980s. They were replaced by biocides based on alternative chemistries, such as 3-iodo-2-propynyl butyl carbamate (IPBC) and 2-n-octyl-4-isothiazolin-3-one (OIT).9-10 Highly effective against fungi, the new chemistries proved to be very capable mildewcides.
These non-mercurial agents, however, did not protect against the bacteria that cause spoilage during storage. As a result, manufacturers were compelled to use preservatives to protect paints in the can. Among the products employed for this purpose were formaldehyde releasers and a number of isothiazolinone compounds introduced in the early 1980s. Although these biocides performed well as in-can preservatives, they were not effective as dry film mildewcides. Consequently, for the past 20 years, paint manufacturers have been compelled to use a combination of biocides for complete antimicrobial protection.